Roll view while looking through camera
As far as I know, if you rotate the camera, the background image will always rotate with it. However, similarly to this question, you can display the image inside of an empty instead of as a background image, and then you can roll your active camera, and the empty displaying the image won't move.



I realize that this isn't a perfect solution since using the empty isn't nearly as easy as just using the background image feature, but it's the best I can come up with.